Isolation and characterisation of Ralstonia solanacearum strains from Solanaceae crops in Ethiopia

Abstract

Eighty one isolates of Ralstonia solanacearum -like bacteria on triphenyl tetrazolium chloride (TTC) medium were collected from different Solanaceae crops (i.e. potato, tomato and pepper plants and potato tubers) at various sites in Ethiopia. Of these, 62 strains were identified as R. solanacearum based on their cultural characteristics on TTC medium, tomato pathogenicity bioassay, carbon source utilisation patterns and a specific PCR-based assay. By Hayward's classification method, based on carbon source utilisation, 19 of the 62 R. solanacearum strains were identified as biovar I and 43 strains were identified as biovar II. The biovar I strains exhibited a high growth rate at high temperatures (37 degrees C). Whereas the growth rate of biovar II strains was greatest at lower temperatures (22 degrees C). Biovar I strains had broader host range than biovar II strains, which were limited to potato, tomato, and eggplant. To our knowledge, this is the first report of R. solanacearum biovar I in Ethiopia. The existence of biovar I strains in Ethiopia raises concerns because they have a broader host range than biovar II strains.

In Vitro Evaluation of Antibacterial Chemicals and Bioagents against Ralstonia solanacearum Infecting Bacterial Wilt in Ginger

“…The well separated colonies were picked up and purified further by single colony isolation technique and then suspended in sterile distilled water in sterile plastic ependorf tubes and stored at room temperature this served as stock culture for further use. Similar results were also reported (Lemessa and Zeller, 2007A;Chakravarty and Kalita, 2011;Chaudhry and Rashid, 2011;Sagar et al, 2014).…”

Molecular characterization of Ralstonia solanacearum strains from Ethiopia and tracing potential source of bacterial wilt disease outbreak in seed potatoes

“…The identification of all R. solanacearum isolates in this study as phylotype II B sequevar 1 strains is in agreement with reports of Yaynu (), Lemaga et al . () and Kassa & Chindi () who reported race 3 biovar 2 from Ethiopia which belongs to phylotype II, but in contrast to Lemessa & Zeller () who also reported race 1 biovar 1 from Ethiopia. Fegan & Prior () grouped biovar 1 strains into phylotype II/sequevar 3–7 and phylotype III/sequevar 19, 22 and 23.…”

“…() deduced that the Ethiopian biovar 1 strains they identified should probably be placed in phylotype III, which was recently placed into the R. pseudosolanacearum genospecies (Safni et al ., ). The assertion that the Ethiopian biovar 1 strains belong to phylotype III needs further investigation as it is also probable that those isolates were from phylotype IIA; phylotype IIA being the more likely case if they were in fact a result of introduction of potato genotypes by CIP, as argued by Lemessa & Zeller (). However, either way, the present study is indicative that race 1 biovar 1 strains were not the key players in the current wide‐scale bacterial wilt disease epidemic on surveyed seed potato fields across Ethiopia.…”

“…Based on phenotypic properties, R. solanacearum has been historically divided into five races (related to the ability of the bacterium to wilt specific plant species) and six biovars (related to the ability of the bacterium to metabolize three sugar alcohols and three disaccharides; Fegan & Prior, ; Wicker et al ., ). Based on this classification scheme, only race 1 biovar 1 (with ability to wilt the Solanaceae family), race 3 biovar 2 (the potato brown rot strains), and race 4 biovar 3 (ginger wilting strains) were reported to be present in Ethiopia (Yaynu, ; Lemessa & Zeller, ; Kifelew et al ., ), race 3 biovar 2 being the dominant genotype infecting the potato crop. However, this classification system is deemed neither predictive nor phylogenetically meaningful for epidemiological inferences (Fegan & Prior, ; Siri et al ., ; N'Guessan et al ., ; Parkinson et al ., ).…”

Isolation and Characterization of <i>Ralstonia solanacearum</i> Causing Bacterial Wilt of Tomato in Nigeria

“…Denny and Hayward (2001) identified race of R. solanacearum by host specifity. The differences in reactions of tobacco leaves and susceptible tomato cultivars to infiltration/inoculation with isolates of R. solanacearum were used as simple and quick means of determining the race of any particular virulent isolate of this pathogen (Lozano and Sequiera, 1970;Lemessa and Zeller, 2007).…”